
\section{Conclusion}\label{sec:conclusion}
\vspace{10pt}
ReRAM is a promising candidate for next-generation
non-volatile memory technology. The area efficient cross-point structure
is the most attractive memory organization for ReRAM memories. However,
problems inherent in the cross-point structure, such as the existence of
sneak current and voltage drops along the wires introduce challenges to
the design of reliable ReRAM cross-point memory arrays. In this paper, we
first develop a mathematical model for cross-point memory arrays. We show
that the proposed model has a simple structure and is flexible enough to
evaluate different write/read schemes. By using this model, we study in
detail how reliability affects the array organization, size, energy
consumption, and area overheads of cross-point arrays. The simulation
results show that multi-bit write operation is more energy efficient than
single-bit write operation, and therefore is more suitable for
energy-constrained design. However, for an area-constrained design,
single-bit write operation is better. Finally, we point out that both
increasing nonlinearity and scaling of write current of the ReRAM cell can
reduce the energy consumption and area overhead significantly, and it is
favorable for large, energy efficient ReRAM design.
